Freeze-drying vacuum valve

ABSTRACT

An all resilient vacuum valve for coupling material to be dehydrated to a freeze dryer in which the valve includes an outer elastomer tubular member for interconnecting the material to the freeze dryer and a stem slidably mounted in the tubular member for opening and closing the valve. The tubular member at its juncture with the freeze dryer is provided with a precision undercut, so precise that it permits not only a convenient snap fit of the valve to the freeze dryer chamber but also prevents accidental removal of the valve from the chamber while at the same time permitting the valve to be stressed considerably in any direction without impairing the vacuum system.

United States Patent 1 Parkinson FREEZE-DRYING VACUUM VALVE lnventor:Martin c. Parkinson, Nyack, NY.

[73] Assignee: Dritron, Incorporated, WestNyack,

[22] Filed: Oct. 31, 1972 [211 Appl. No.: 302,619

[52] US. Cl 137/625.-24, 137/589, 285/DIG. 22 [51] Int. Cl. F16k 11/07[58] Field of Search l37/625.24, 556.6,

Primary Examiner-Henry T. Klinksiek Assistant Examiner-Robert .1. MillerAttorney-Leo C. Krazinski [57] ABSTRACT An all resilient vacuum valvefor coupling material to be dehydrated to a freeze dryer in which thevalve includes an outer elastomer tubular member for interconnecting thematerial to the freeze dryer and a stem slidably mounted in'the tubularmember for opening and closing the valve. The tubular member at itsjuncture with the freeze dryer is provided with a precision undercut, soprecise that it permits not only a convenient snap fit of the valve tothe freeze dryer chamber but also prevents accidental removal of thevalve from the chamber while at the same time permitting the valve to bestressed considerably in any direction without impairing the vacuumsystem.

10 Claims, 6 Drawing Figures FREEZE-DRYING VACUUM VALVE BACKGROUND OFTHE INVENTION 1. Field of the Invention The present invention relates tovalves and, more particularly, to valves for use in freeze-drying,whereby air and other vapors are evacuated from a product.

2. Description of the Prior Art In conventional manifold freeze-dryingprocedures, metal tubes (ports) are welded to openings in vacuumchambers or tubular manifolds. Once the proper'number of tubes (ports)have been welded to thevacuum chamber or tubular manifold, rubber valvesof various types are fitted over the tubes, as is evident in U.S. Pat.No. 3,6l2,l of Oct. l2, l97l. In certain manifold freeze-dryer designsit is also necessary to weld a metal baffle plate behind each openingeither to prevent ice blockage of the port, if the vapor condenser isvery near the port opening, or to prevent crosscontamination of theproduct if ports are near and directly opposite each other, as may bethe case in tubular manifold designs.

In conventional operation, a refrigerated condenser (mechanical freonrefrigeration, or dry ice, or liquifled gases) is placed within thevacuum chamber and samples to be freeze-dried are placed in containers,such as serum bottles. The contents of the bottle is'pre-frozen byrotating the bottle in a dry-ice/solvent bath or other,

suitable means of freezing the product. The bottle is then connected toone of the rubber valves on the vacuum chamber or tubular manifold.Under the influence of the vacuum and the ambient room temperature, icewithin the bottle sublimes directly from the frozen to the vapor state,by-passing the intermediary liquid phase. This drying is so gentle thatwhen water is added to the dried product it reconstitutes to virtuallythe identical original product.

It has been found that, as currently fabricated, the large amount ofintricate welding required at each port provides an excessiveopportunity for vacuum leaks to occur. Also, corrosion may occur in amatter of a few years (and sometimes in a few months), particularly atthe welded points. Also, vacuum leak detection is difficult oftenrequiring return of the equipment to the manufacturer for repair orexpensive factory trained field service representative repair.

SUMMARY OF THE INVENTION Accordingly, an object of the invention is 'toprovide such apparatus for freeze-drying material which overcomes thedisadvantages and difficulties heretofore encountered.

Another object is to eliminate all welds and merely cut holes in thevacuum chamber or tubular manifold, whereby the excellent corrosionresistance of the steel remains the same.

Another object is to provide apparatus that is substantially leak proof.

Another object is to provide an improved valve for coupling the materialto be freeze-dried to the perfo-' rated vacuum chamber or tubularmanifold.

A further object is to accomplish the foregoing ina simple and practicalmanner.

Other and further objects will be obvious upon an understanding of theillustrative embodiment about to be described, or will be indicated inthe appended claims and various advantages not referred to herein willoccur to one skilled in the art upon employment of the invention inpractice.

BRIEF DESCRIPTION OF THE DRAWING A preferred embodiment of the inventionhas been chosen for purposes of illustration and description and isshown in the accompanying drawing, forming a part of the specification,wherein:

FIG. 1 is a side elevational view ofa vacuum valve attached to a freezedryer manifold in operative use, in

accordance with the present invention.

FIG. 2 is an end elevational view of the valve in the direction of thearrow 2 in FIG. 1.

FIG. 3 is a longitudinal sectional view of the valve taken along line3-3 of FIG. 2 illustrating the details of the valve while in theinoperative position.

FIG. 4 is a sectional view taken along line 4-4 of FIG. 1 showing thestem and main valve sleeve openings within the freeze dryer chamber inregistration.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 1 showing thestem and tubular member openings in registration.

FIG. 6 is a sectional view taken along line 66 of FIG. 1 with the stemrotated from that shown in FIG. 3 and with the vent hole and ventingslot in registration.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 m6 ofthe drawing, there is shown a vacuum valve 10 removably attached to afreeze-dryer vacuum chamber or tubular manifold 11 and carrying a bottle12 containing a product to be freeze-dried. As seen in FIG. 3, the valve19 consists of two parts, an outer sleeve 13 and an inner tubular stem14. Preferably, the sleeve 13 is-made of silicone rubber so as toclearly see open and closed positions of the valve and the stem 14 ismade of polypropylene for its unbreakable long life. The durometer ofsleeve 13 is preferably between 35 50, Shore A, although softer andharder rubber durometers may be used.

The sleeve 13 has a transverse vent opening 16 adjacent its inner endand at its innermost end larger opposed transverse openings 17 fordisposition within the chamber 11. The sleeve 13 is open at one end andhas its other end 18 tapered with a closed end wall 19 or baffle withinthe chamber 11, and between the openings 16 and 17 is shown a shoulder20 in abutting engagement with a manifold wall 21 of the chamber 11. Atthe inner side of the shoulder 20 is provided a precision undercut orgroove 22, which will be covered in greater detail hereinafter. Adjacentthe outer end of the sleeve 13 is integrally formed at an angle a secondopen-ended sleeve or tubular member 23 having a bore 24 in communicationwith a bore 26 of the sleeve 13. The open end of the sleeve 23 isadapted to carry the bottle 12 or other container to be evacuated.

The stem 14 is shown formed with a head 27, preferably of squareshapewith concave sides 28 for easein manipulation, a tubular shankportion 29 and a solid shank portion 31 interconnecting the head 27 andtubular shank portion 29. The tubular shank portion 29 is provided witha transverse inlet opening 32 adjacent the solid shank portion 31 forregistration of the bores 24 and 26 when the valve 10 is in itsoperative or open position, that is, when the stem 14 is pushed into theouter sleeve 13, as shown in FIG. 1. The innermost end of the stem 14 isshown with opposed openings 33, preferably open ended slots; thediameter of the stem 14 from its inner end for a distance of aboutone-half inch has a reduced portion 34, where the stem enters the vacuumchamber 11, and the stem 14 is also provided along its peripheralsurface with a longitudinal slot 36 which interconnects the vent opening16 with the bore 24 for bleeding air into the bottle 12 when the stem 14is rotated l80 from that shown in FIG. 3.

Returning now again to the precision undercut 22, which meshes with themanifold wall 21, as seen in FIG. 3, and which permits a convenient snapfit of the valve 10 to chamber 11, it also prevents accidental removalof the valve and permits the valve to be stressed or flexed to anextreme degree in any direction without impairment of system vacuum.Since the dimensions of the undercut 22 are critical, it is best to giveexamples illustrating the same, (-a) one with a 25 inch OD. and (b)another with a 4 inch O.D. stem. In the case of the k inch stem, thedimensions of the outer sleeve 13 are 1 inch O.D. X b inch ID. and theopening in the chamber 11 is three-fourths inch. A 0.18 inch deep by0.015 -0'.0l8 inch wide undercut 22 in the outer sleeve 13 with itstapered end portion 18 permits convenient coupling to the chambermanifold wall 21, as is evident in FIG. 3. When the stem 14 is theninserted into the sleeve 13, the bulbous portion 37, which was displacedinwardly when the sleeve 13 was inserted in the manifold wall 21, isexpanded outwardly to form a high vacuum tight seal.

In the case of the inch stem, a simple increase of one-fourth inch inall sizes is merely required, that is, 1 inch diameter opening in thechamber wall and l% inch O.D. X inch ID. of the sleeve 13, but with thesame dimensions of undercut, that is, 0.18 inch deep by 0.015 0.018 inchwide. A high vacuum tight seal is provided thereby. It is believed thatthe same proportion can be used for a stem A inch CD. as well as for astem 1% inch O.D.

To operate satisfactorily close tolerance must be maintained,particularly for the precision undercut 22. The depth of the undercutshould not vary more than :t 0.40 inch within the framework of the othervalve dimensions. The valve must maintain a high vacuum tight seal, yetthe stem 14 must rotate easily and the valve must be capable of bendingto a severe degree when a heavy bottle 12 or container is connected tothe vapor inlet tube 23. Too little undercut will prevent turning thestem 14 and too much undercut will cause the valve 10 to leak whenflexed.

Another important dimension of the valve is the reduced portion 34 atthe inner end of the stem 14. In the previous examples given where stem14, OD. dimensions are given as one-half inch, this refers toapproximately a 7% inch length at the end of the stem 14. The remainingCD. of stem 14 is slightly larger in all cases, typically +0.030 inch,that is, 0.530 inch and 0.780 inch for 1% inch and 54 inch O.D. stems,respectively. The reason for the two dimensions for each stem 14 0D. isas follows:

As this reduced portion 34 of about one-half inch in length enters thechamber 11, it expands the rubber bulbous portion 37, thereby looseningthe close fit of the stem 14 and tubular shank portion 29 outwardstoward the rubber vapor inlet tube 23. When flask 12 is connected tothis tube, air would leak through vent hole 16 and channel its waythrough to the vapor inlet opening 32 in the 'stem 14 if the stem 14 hadthe same O.D. along its entire length.

In operation, the outer sleeve 13 of the valve 10 with its tapered endportion 18 is readily inserted into an opening of the freeze-dryermanifold 21 and snapped into position by virtue of the precisionundercut 22. In FIG. 3 note the bulbous portions 37 brought about by thecompression of the manifold 21 on the sleeve and that the stem 14 is inthe withdrawn position. Also, the inner face of the shoulder 20 bearsagainst the manifold wall 21 and thus prevents further insertion of thevalve sleeve 13. The stem 14 is rotated 180 from that shown in FIG. 3,that is, with inlet opening 32 at the top and the longitudinal slot 36at the bottom, and then pushed through the bore 26 of the sleeve untilthe head 27 rests against the open end of the sleeve 13, as shown inFIG. 1. The valve is now in the closed or inoperative position and thevacuum system can be placed in operation. The bottle 12 may now beinserted into tubular member 23, see FIG. 6. The stem 14 is then rotated180 to register inlet openings 32 with the bore 24 and bore 26 of thesleeve, whereupon evacuation of the bottle takes place.

During evacuation it is to be noted that there is a high velocity ofwater molecules flowing from the bottle 12, which molecules strike theend wall 19. The end wall functions as a baffle to force the moleculesout through opposed holes 17. There is a slight increase in pressure ateach of these two openings 17 causing the molecules to take a momentarydirectional path parallel to tbe openings and then, almost immediately,the molecules take on a purely random path tothe surface of thecondenser, inner pot (not shown) to which they adhere, that is, freezeand are no longer in the system. Thus, the baffle design insures a morerandom and more uniform condensing of the water vapor and thereby takesmaximum advantage of the available condenser surface.

This baffle, therefore, greatly increases the single run ice condensingcapacity of the condenser in manifold freeze-dryer designs which placethe condenser immediately' adjacent to the port opening.

Another advantage of baffle 19 occurs in tubular manifold freeze-dryerdesigns in which the port openings are directly opposite each other andat a relatively short distance (2 inch or 3 inches) from each other.Some portion of the solid material to be dried often escapes duringfreeze-drying and in the absence of a baffle may find direct access toanother container. Prevention of cross-contamination is particularlyimportant when drying different bacterial cultures at the same time onthe same manifold.

Upon completion of evacuation the stem 14 is rotated the inlet openingis closed and the vent opening 16 is in registry with the longitudinalslot 36, which in turn is in communication with the bore 24 of thetubular member 23. Accordingly, the bottle 12 is vented gradually afterwhich the bottle may be removed and another bottle substituted and thecycle repeated.

From the foregoing description it will be seen that the presentinvention provides an improved vacuum valve for freeze-dryers wherein bythe use of clear silicone rubber for the sleeve open, closed and ventpositions are directly observed.

As various changes may be made in the form, construction, andarrangement of the parts herein, without departing from the spirit andscope of the invention and without sacrificing any of its advantages, itis to be understood that all matters are to be interpreted asillustrative and not in any limiting sense.

What is claimed is:

1. A vacuum valve for connecting a container to be evacuated to a freezedryer chamber, having an opening in a manifold wall thereof comprising,in combination, a first elastomer tubular member having an open end anda closed end with at least one opening, a second elastomer tubularmember integral with said first tubular member intermediate said endsand extending at an angle from said first tubular member, said secondtubular member being in communication with said first tubular member attheir juncture and open at its free end for air tight support of saidcontainer, said first tubular member being adapted to have its closedend inserted through said chamber opening into said chamber and aportion of said first tubular member adjacent said closed end beingseated upon said manifold wall at said chamber opening, a stem slidablyand rotatably mounted in said first tubular member having an opening foropening and closing said valve, and means including a shoulder andundercut portion adjacent said closed end of said first tubular memberfor precision securement of said valve to said chamber.

2. A vacuum valve according to claim 1, wherein said undercut portionconsists of a circumferential groove of predetermined width and depth onsaid first tubular member between said shoulder and said closed end.

3. A vacuum valve according to claim 2, wherein said predetermined widthand depth of said undercut portion are 0.18 inch deep by 0.015 0.018inch wide for a k or 34 inch diameter stem.

4. A vacuum valve according to claim 3, wherein the depth of theundercut should not vary more than i 0.040 inch.

5. A vacuum valve according to claim 2, wherein an innermost end of saidstem has a reduced diameter of about one-half inch along its linearlength.

6. A vacuum valve according to claim 2, wherein said first tubularmember is of clear silicon rubberf 7. A vacuum valve according to claim2, wherein said stem opening is adapted for communication with saidfirst and second tubular members when said valve is in an open conditionand out of communication when said stem is rotated to place said valvein a closed position.

8. A vacuum valve according to claim 7, wherein said first tubularmember has a vent opening and said stem has a longitudinal slot alongits peripheral length for communication with said vent opening and saidsecond tubular member for venting said container.

9. A vacuum valve according to claim 8, wherein said closed end of saidfirst tubular member has a pair of opposed openings and said closed endacts as a'baffle to direct fluid flow'from said container through saidopposed openings in said first tubular member into said chamber.

10. A vacuum valve in accordance with claim 9, wherein said stem hasopposed openings at its innermost end for communication with saidopposed openings in said first tubular member when said valve is in anopen condition.

1. A vacuum valve for connecting a container to be evacuated to a freezedryer chamber, having an opening in a manifold wall thereof comprising,in combination, a first elastomer tubular member having an open end anda closed end with at least one opening, a second elastomer tubularmember integral with said first tubular member intermediate said endsand extending at an angle from said first tubular member, said secondtubular member being in communication with said first tubular member attheir juncture and open at its free end for air tight support of saidcontainer, said first tubular member being adapted to have its closedend inserted through said chamber opening into said chamber and aportion of said first tubular member adjacent said closed end beingseated upon said manifold wall at said chamber opening, a stem slidablyand rotatably mounted in said first tubular member having an opening foropening and closing said valve, and means including a shoulder andundercut portion adjacenT said closed end of said first tubular memberfor precision securement of said valve to said chamber.
 2. A vacuumvalve according to claim 1, wherein said undercut portion consists of acircumferential groove of predetermined width and depth on said firsttubular member between said shoulder and said closed end.
 3. A vacuumvalve according to claim 2, wherein said predetermined width and depthof said undercut portion are 0.18 inch deep by 0.015 - 0.018 inch widefor a 1/2 or 3/4 inch diameter stem.
 4. A vacuum valve according toclaim 3, wherein the depth of the undercut should not vary more than +or - 0.040 inch.
 5. A vacuum valve according to claim 2, wherein aninnermost end of said stem has a reduced diameter of about one-half inchalong its linear length.
 6. A vacuum valve according to claim 2, whereinsaid first tubular member is of clear silicon rubber.
 7. A vacuum valveaccording to claim 2, wherein said stem opening is adapted forcommunication with said first and second tubular members when said valveis in an open condition and out of communication when said stem isrotated to place said valve in a closed position.
 8. A vacuum valveaccording to claim 7, wherein said first tubular member has a ventopening and said stem has a longitudinal slot along its peripherallength for communication with said vent opening and said second tubularmember for venting said container.
 9. A vacuum valve according to claim8, wherein said closed end of said first tubular member has a pair ofopposed openings and said closed end acts as a baffle to direct fluidflow from said container through said opposed openings in said firsttubular member into said chamber.
 10. A vacuum valve in accordance withclaim 9, wherein said stem has opposed openings at its innermost end forcommunication with said opposed openings in said first tubular memberwhen said valve is in an open condition.